Method for Determining the Azimuthal Orientation of a Patient Eye and Eye Surgical Apparatus Therefor

1. An eye surgical apparatus comprising: imaging optics for generating observation images of a patient eye; and, a device for determining and displaying an azimuthal orientation of the patient eye with respect to a reference fixed with respect to the patient eye; said device including: a visual display unit configured to simultaneously display: a section, composed of pixels, of a captured observation image of the patient eye captured by said imaging optics; said section containing at least one segment of a sclera and being displayed as a first rectangular image strip representing, in polar coordinates, a first annular image segment of the captured observation image; a reference image, composed of pixels, of the patient eye and containing said at least one segment of the sclera being displayed as a second rectangular image strip representing, in said polar coordinates, a second annular image segment of the reference image; and, said first and second image strips being displayed mutually parallel to one another in a mutually adjoining manner; an input interface configured to permit an observer to effect a linear movement of the first rectangular image strip representing the first annular image segment of the captured observation image of the patient eye relative to the second rectangular image strip representing the second annular image segment of the reference image whereby an azimuthal orientation of said captured observation image relative to said reference image changes during said linear movement; a measuring system configured to determine a change of azimuthal orientation of the captured observation image relative to said reference image because of said linear movement; a computer unit having a computer program for computing the center of a first circular structure of a limbus and/or of an iris of said captured observation image and for computing the center of a second circular structure of the limbus and/or of the iris of said reference image; and, said visual display unit being further configured to display said pixels of said captured observation image with polar coordinates having a center coincident with the computed center of said first circular structure and to display said pixels of said reference image with polar coordinates in a polar coordinate system having a center coincident with the computed center of said second circular structure.

2. The eye surgical apparatus of claim 1 , wherein said input interface is a first input interface and said first strip defines a longitudinal axis; said eye surgical apparatus comprises a second input interface configured to provide shift signals; and, wherein said pixels in said first image strip are shiftable along said longitudinal axis in response to a first one of said shift signals specified at said second input interface; and/or, said pixels in said second strip are shiftable in response to a second one of said shift signals specified at said second input interface.

3. The eye surgical apparatus of claim 2 , wherein said second input interface is a touch-sensitive user interface of said visual display unit.

4. The eye surgical apparatus of claim 1 , wherein said visual display unit is a first visual display unit and said device for determining azimuthal orientation of the patient eye further includes a second display unit for displaying said change in the azimuthal orientation of said captured observation image relative to said reference image as determined with said measuring system.

5. The eye surgical apparatus of claim 4 , wherein said computer unit has a computer program for computing a change in an azimuthal orientation of the patient eye based on said change determined with said measuring system and on a direction of the astigmatism of the patient eye stored in a data memory of said computer unit and based on a reference.

6. The eye surgical apparatus of claim 5 , wherein said reference is said reference image.

7. The eye surgical apparatus of claim 5 , wherein said computer unit is configured to generate an item of display information, which is superposed on said captured observation image of the patient eye, in order to display the direction of the astigmatism of the patient eye on said captured observation image.

8. The eye surgical apparatus of claim 7 , wherein said display information is an astigmatism axis.

9. The eye surgical apparatus of claim 7 , further comprising a surgical microscope defining an object plane and accommodating said imaging optics; said surgical microscope including: a binocular viewer to facilitate viewing through said imaging optics; and, a reflecting device for reflecting in data; and, said reflecting device including a display connected to said computer unit and said display being configured to display said display information in said binocular viewer in a manner superposed on an operating area in said object plane.